The invention relates generally to ink cartridges such as for ink jet printers, and in particular to a method of filling an ink supply bag to be included in an ink cartridge.
Prior art U.S. Pat. No. 5,950,403 issued Sep. 14, 1999 discloses a method of filling an ink supply bag with a liquid ink. The filled bag is included in an ink cartridge for an ink jet printer.
According to the disclosed method, the ink supply bag is hung vertically so that a bottom end of the bag faces downward and a top end of the bag faces upward. A liquid ink is flowed into the bag through an opening in the top end and the bag is filled to about 60% of its height, i.e. to a liquid level below an upper portion of the bag. Then, the bag is squeezed below the upper portion to raise the liquid level partway into the upper portion. Next, the upper portion is temporarily sealed below the liquid level in the upper portion so that some liquid ink in the upper portion is above the temporary seal. Then, the bag is released from being squeezed, and any air bubbles in the liquid ink are allowed to aggregate just below the temporary seal in the upper portion. Then, the bag is re-squeezed below the upper portion, but this time more than the first time, and the upper portion is permanently sealed below the temporary seal. This causes a bulge to be formed in the upper portion between the respective seals and traps a small quantity of liquid ink that includes the bubbles in the bulge. Finally, the upper portion is cut along a centerline of the permanent seal, and the remainder of the upper portion above the permanent seal is discarded.
The disclosed method is an attempt to ensure that any air bubbles in the liquid ink are removed. However, since the temporary seal is below the liquid level in the upper portion, the additional liquid above the temporary seal can splash or spill out of the opening in the top end of the bag. Also, the additional liquid above the temporary seal increases the quantity of liquid ink that must be wasted or discarded.
According to the invention, a method of filling an ink supply bag with a liquid ink, comprises:
positioning the bag bottom end down and a top end up;
flowing the liquid ink into the bag through an upper portion of the bag to fill the bag to a liquid level below the upper portion;
squeezing the bag to raise the liquid level in the bag partway into the upper portion, and shaking the bag to cause any bubbles in the liquid ink in the bag to rise at least substantially to the liquid surface in the upper portion; and
sealing the upper portion above and below the liquid level in the upper portion to trap a small quantity of liquid ink that includes the bubbles and a small quantity of air between the respective seals.
Thus, the quantity of liquid ink that cannot be used is reduced as compared to prior art U.S. Pat. No. 5,950,403. Moreover, there can be no spillage of the liquid ink since there is no liquid ink in the upper portion above the uppermost seal as in prior art U.S. Pat. No. 5,950,403.